Polysorbate 20 is a gentle, non-irritating, non-toxic solubilizer.

What's a solubilizer?
A solubilizer is necessary to emulsify fragrance and essential oils with various bases -- most commonly shampoo, shower gel, liquid soap, and creams and lotions.
What happens if I don't use a solubilizer?
You'll get a yucky, stringy, opaque, mucous-y mess. The result is unusable, and unsellable.
Oooh, ishy! How do I use the Polysorbate 20?
Combine equal amounts of Polysorbate 20 and the essential and/or fragrance oils you plan to use. Combine well, and add while stirring gently to your base (lotion, shower gel, etc.). If the base has thickened noticeably, add more Polysorbate 20 as needed.

INCI Name: Polysorbate 20

Flashpoint: >500* F

Irish Spring (type) Fragrance

Purely Herbal Fragrance

Farmhouse Travel Bar Soap Mold

Bay Rum Fragrance